Reloading texture with python not working
Hi in addition to what J. Bakker said, here is some code that I used in TexTools addon to reload all images and remove unused ones.

import bpy

# Clean up unused images
for img in bpy.data.images:
    if not img.users:
        bpy.data.images.remove(img)

#Reload all File images
for img in bpy.data.images :
    if img.source == 'FILE' :
        img.reload()


Hope this helps,

renderhjs